Liquid level switch



July 24, 1956 E. M. SUTTON 2,756,301

LIQUID LEVEL SWITCH Filed April 27, 1953 38 Emerson M. Suffon INVENTOR.

United States Patent LIQUID LEVEL SWITCH Emerson M. Sutton, Norfolk, Va.

Application April 27, 1953, Serial No. 351,351

2 Claims. (Cl. 200-83) This invention relates to liquid level actuated electric switches of the diaphragm type and has for its primary object the provision of a liquid level switch capable of adjusting itself automatically to compensate for changes in the atmospheric pressure.

In the switches of the single diaphragm design used for controlling liquid level, the liquid rising within the tube or chamber compresses the air that is trapped therein by the rising liquid to thereby increase the pressure thus actuating the diaphragm so as to close a pair of contacts to complete an operative electrical circuit. The contact could readily be caused by a rise in the atmospheric pressure, and such contact would be continuous until the atmospheric pressure decreased. Further, if the atmospheric pressure were to be decreased it is quite probable that the rising of the liquid within the tube will not cause the air pressure within the tube to increase enough to properly actuate the diaphragm to close the electrical contacts. It is, therefore, another object of this invention to provide a substantially air-tight and water-tight liquid level switch which employs a pair of diaphragms, one of which diaphragms is used to actuate a switch contact member, the other diaphragm being used to compensate for atmospheric pressure to move the other contact member in response to these changes.

The most important features of this invention include the pair of diaphragms which carry the contact members of the electric switch. One of the diaphragms actually carries one of the contact members while the other diaphragm carries an actuating lever to which there is attached the other contact.

Still further objects and features reside in the provision of a liquid level switch that is strong, durable, highly efficient in operation, simple in construction and manufacture, and which is formed of a minimum number of parts so as to be relatively inexpensive to produce.

These, together with various ancillary objects and features of the invention which will become apparent as the following description proceeds, are attained by this liquid level switch, a preferred embodiment of which has been illustrated in the accompanying drawings, by way of example only, wherein:

Figure 1 is a vertical sectional view of the liquid level switch comprising the present invention, which shows in greatest detail the construction of the compensating means for atmospheric pressure; and

Figure 2 is a top plan viewof this device, with parts being broken away to show all the parts in greater detail.

With continuing reference to the accompanying drawings wherein like reference numerals designate similar parts throughout the various views, reference numeral is used to generally designate a base to which the various elements of this invention are secured. The base 10 is provided with a pair of apertures 12 and 14 therethrough and is further provided with suitable legs 16 for supporting the base.

Closing the apertures 12 and 14 are diaphragms 18 and 20 which may be constructed from any suitable flexible material and which are secured in position by being cemented, or may be otherwise attached by any well-known mediums. A diaphragm ring 22 is provided for securing the ends of the diaphragm 20 about the aperture 14 and for reenforcing such. A flanged conduit 24 is provided and is secured below the diaphragm 18 for trapping air between the flow of water entering the conduit 24 and the diaphragm.

Carried by the diaphragm 18 is a contact 26 having a contact 28 attached thereto. An actuating lever 30 is mounted on a plate 32 carried by the diaphragm 20. The actuating lever 30 carries a contact 34 adapted to engage under ascertained conditions with the contact 28.

A suitable air-tight and water-tight casing 36 is secured by means of screws 38 to the base 10. A suitable gasket 40 is used to insure the proper seal between the casing 36 and the base 10. An electrically conductive cable 42 is led in through the casing and is sealed by suitable bushing 44 to further insure the water-tight integrity of the switch. The cable 42 includes two conductors 46 and 48 which are electrically operatively connected to terminals 50 and 52 on the plates 26 and 32 respectively.

In operation, when the pressure of the air outside of the casing 36 is greater than the pressure of the air inside the casing 36 the diaphragms 18 and 20 will both respond. The diaphragm 20 will move the actuating lever 30 so as to maintain a suitable distance between the contacts 28 and 34. When liquid begins to rise within the conduit 24, it seals off the conduit 24 and stops the equalizing action between the two diaphragms 18 and 20. As the liquid continues to rise it compresses the air which causes the diaphragm 18 to deflect to thus cause contact 28 to engage contact 34. As the liquid level drops, the tube or conduit 24 will again be above the level of the liquid and atmospheric pressure will act on both diaphragms and equalizing action will again take place. This action will automatically adjust the switch for any changes in the atmospheric pressure either up or down.

Since from the foregoing, the construction and advantages of this liquid level switch are readily apparent, further description is believed to be unnecessary.

However, since numerous modifications will readily occur to those skilled in the art, after a consideration of the foregoing specification and accompanying drawings, it is not intended to limit the invention to the precise embodiment shown and described, but all suitable modifications may be readily resorted to which fall within the scope of the appended claims.

What is claimed as new is as follows:

1. A liquid level actuated switch comprising a base, a pair of spaced apertures in said base, a conduit secured in alignment with one of said apertures, diaphragms secured to said base closing said apertures, a first contact member carried by a first of said diaphragms, an actuating lever having a second contact member depending therefrom carried by the other of said diaphragms, said second contact member being engageable with said first contact member upon actuation of said first diaphragm, said actuating lever extending above said first diaphragm, said conduit extending substantially below said first diaphragm below said first contact and being open at the bottom end thereof, and a water-proof cover secured in Water-proof engagement to said base, a pair of electrical leads extending into said water-proof cover and secured in electrical connection with said contacts, and means for water-proofing the intersection of said electrical leads with said water-proof cover.

2. A liquid level actuated switch comprising a base, a pair of spaced apertures in said base, a conduit secured in alignment with one of said apertures, diaphragms secured to said base closing said apertures, a first contact member carried by a first of said diaphragms, an actuattherefrom carried by the other of said diaphragms, said second contact member being engageable with said first contact member upon actuation of said first diaphragm, said actuating lever extending above said first diaphragm, said conduit extending substantially below said first diaphragm below said first contact and being open at the bottom end thereof.

References Cited in the file of this patent UNITED STATES PATENTS I 4 Bristol Apr. 17, Zeiher et a1 Apr. 27, Nicholson Sept. 13, Flubacker July 11, Hunter et a1. Oct. 21, Wilson Apr. 14,

FOREIGN PATENTS Great Britain Jan. 18, 

